1. Field of the Invention
The invention relates generally to containers for transporting or storing liquids or freely flowable solids. Specifically, the invention relates to collapsible, reusable, and stackable intermediate bulk containers.
2. Description of Related Technology
Intermediate bulk containers are used for shipping and storing liquids such as chemicals, beverages, or food products, or freely flowable solids such as grains, livestock feeds, chemicals in powder form, and minerals in powder form. Recent designs for rigid intermediate bulk containers have typically been rectangular in shape. It is desirable to be able to move bulk containers using a fork lift and to stack them to maximize the use of storage and shipping space. To perform this function, many types of bulk containers include pallet-type bases that are compatible with standard fork lifts. Rigid bulk containers present a problem of wasted space in storing or shipping the containers when empty.
The problem of wasted space has been addressed by the development of flexible bag type bulk containers that are well known in the art. For example, LaFleur, et al., U.S. Pat. No. 4,596,040 discloses a generally rectangularly shaped large bulk bag formed from a tubular blank of woven fabric. Such flexible bag containers are used for dry material shipping and storage and are desirable for use in storing and shipping liquid or freely flowable solid materials. They cannot, however, be used for shipment or storage of liquid or freely flowable solid materials unless structural support is provided. Flexible bag containers can also be sterilized and used in conjunction with "tamper evident" seals on inlet and outlet fittings, for example, for use when holding food products.
In order to stack flexible bag containers and ensure the stability of a flexible bag container when full and in shipment, it is often desirable to reinforce the container by attaching it to a rigid frame. This is particularly important for storage and shipment of liquid materials. It is also desirable for the rigid frame to be capable of collapsing for transport or storage once the container is empty. Collapsible rigid frames for this purpose are disclosed in LaFleur et al., U.S. Pat. No. 4,817,824, D'Hollander, U.S. Pat. No. 5,269,414, and Potter, U.S. Pat. No. 2,720,998. Similarly, collapsible rigid frames for holding flexible bag containers are available commercially under the trademark CONCERTAINER.RTM., from Van Leer Containers, Inc., 4300 West 130th Street, Chicago, Ill. 60658, under the trademark FLEXITOTE.TM., from Hoover Materials Handling Group, Inc., 2001 Westside Parkway, Suite 155, Alpharetta, Ga. 30201, and under the trademark FLUTAINER.RTM., from B.A.G. Corp., 11510 Data Drive, Dallas, Tex. 75218.
The aforementioned collapsible rigid frames, when used in conjunction with a flexible bag container, are not configured to be collapsed until the flexible bag is empty. This is a disadvantage because if the rigid frame could collapse gradually, the weight of components of the rigid frame disposed above the flexible bag could serve to provide a downward force on the flexible bag, thereby assisting in the emptying of the contents of the flexible bag.
In addition, the collapsible rigid frames require manual separation of components of the frame for collapsing, usually by two people, and this presents the possibility of losing components of the frame. The available collapsible rigid frames must also be set up before the container held by thereby can be filled.